In normal operation, the air mass flow meter is subject to effects such as soiling and ageing. Those effects cause divergence between the stored characteristic and the specified status resulting in symptoms such as lack of power or black smoke. In order to prevent the effects of this problem, the 'Air mass flow meter adaptation' function has been introduced on the DDE5.
Air mass flow meter adaptation is performed by the DDE control unit at two operating points: When idling and under load in an operating range defined as follows:
Adaptation sequence at each of those points:
The air mass flow meter adaptation uses certain operational data to calculate the theoretical air mass flow passing through the engine. The DDE control unit compares the figure obtained with the level measured by the air mass flow meter.
If the DDE control unit finds that the measured level differs by more than ± 8% from the theoretical figure, that difference is stored on the control unit as a compensation factor.
That compensation factor enables the control unit to adjust the measured levels before they are processed by the various functions.
The service function Air mass flow meter adaptation must be run if the air mass flow meter is replaced. The stored compensation factors are reset to 0 in the process.
The air mass flow meter adaptation is used as follows: